Apparatus for forming metallic films on tubular carriers



Sept. 12, 1950 s. A. JOHNSON ETAL 2,522,272

I APPARATUS FOR FORMING METALLIC FILMS 0N TUBULAR CARRIERS Filed Nov. 2, 1946 2 Sheets-81199121 v ,lulllllll fifan/gg A. Johnson Huber? W Schleuni q Sept. '12, 1950 s. A. JOHNSON E' I'AL 2,522,272'

APPARATUS FOR FORMING METALLIC FILMS 0N TUBULAR CARRIERS Filed Nov. 2, 1946 2 Sheeis-Sheet 2 WWAQ4W auww,

Patented Sept. 12, 1950 UNITED PATENT 1' APPARATUS: FOR 'FORMING'METALLIIS :FILMS'fiN "EARzRIERS Stanley Adams .LIohnson, New, York, ,andfiubeht Schlefining, Brooklyn, N. "iY.," assignorsfio -='Poly-teelmic' Institute of -Brooklyn, Brooklyn,

N. 736., a corporation ofNew York Application 'Noyember 2, 1946, Serial .No'. 707 ,13'98 '-A further object of the invention to devise apparatus for simultaneously ;ap.plyi:ng coatings to a plurality of tubular --carrierstin :such manner that the'ooatings oniail iof-Jthe carri-ers will be uniform.

"Another 'fe'atunelof theiin vention is-to provide arrangements; for securm different thickness-of t-hexooating on different :areas of the-carrier.

While the invention is especially ..iiesigned for the ioimation-iiof metallic films on tubular carriers's-it may also he 'used'ior; (111?.Desitime;'films-(on plate/alike carriers; or other formsof carriers.

in depositing metallic rfilms :by thermalwevaporation, itzhas been :noted that the molecular ra diationtis not uniform in all directions,-:andwher.e a number .of objects arebeing .coatedsimultaneously, the coatings on the difierent. articles will :not .be exactly the same-due to id-iiterence in H'Claims. (01.91-42.29

' coating apparatusinvolving the rotary head intensity :Qf radiation in diiterent directions from thewap rizin tfi'lament This difli-eu-lt ishoyercome :in the present invention by providing :a movable {carriage for =asupporti n 'the insulating marriers "to be "heated. The imovable "carriage is arranged to continuouslymove the *GELTTiGFS'iGOHI- pletel-y around'aa closed path lone or more times during-the coating hroeess. each -carrier successively moves -into the i'xosi-tion former-1y occupied by :every :oiflaer carrier, and there will be {no variation the -coatings on the aiifferent carriers by reason lot the location" of the carriers at different .positioris with respect to the source of '1 radiation. Preferably, the {movable carriage is the .-form 0f a rotary :Phead aural-le d o moveztheicarriersztn aioircularpath in"merrsy'-,-;goround fashion, although-the imientian-- is mot limited ztothisspecifio-embodiment.

:Jnthe ease of" tubular carriers, theirotaryxcarriage. is also provided with rotating spindles on WhiChlthB tubular canriers x are mounted and are turned about their "respective axes while heing moved in 'the Zeiosed path .as already-described.

The 'preferred :form'zof the "invention is illustrated int-he accompanying drawing inzwhi'eh Fig-u're '1 'is a plan view of xtheirotary'headwwith thefheatshield removed;

Figure 2 is a'sideielevationaryiewzshowing the mounted within a vacuum bell ja'rl FigureB isiaside elevational yiew, partlyin section, showing the detailslof 'th'egrotary head on "aiarger scale than' ifiigures '1 and '2; "and "Figure 4"is a fragmentary View showingfthe underside of the rotary head. I

Referring to "Figure '2 of.thedrawing,' the evaporation apparatus illustrated is substantially. the same'as that s'hown"'arid described in the 'copending' application 'of' ErnstWeber and Stanley A. J ohnsonentitled Formation of Metallic Films by Thermal, Evaporation, "filed Septemberzfi, 194.6. 'The present invention is jeoncerned' only with that part o'fthe evaporation apparatus which constitutes the rotary head; including "the "arrangement "selected parts of the carriers, lto'getherwith the arrangement for heating the carriers duringthe evaporation process. The apparatus involves a"glass bell jar I seated upon a' base plate 2 which is provided with an opening at the tenter thereofand connected with a'suitable evacuatin -systemrnot shown. Four vertical rods or standards 2a, .217 2c and were mounted -upon-plate-2 within hell 1 andare provided wit'h reducd extensions on their lipper ends. "A terminal-"plate 3 mounted above the center of thebase' plate-2 and carries on the upper face thereof a pair of vertical terminal posts 4 and"5--between"which is mounted :ah'eater filament-t for vaporizing the-film forming-material.

While only one filament 'is shown in the 'drawing for the purpose of illustration, itwill be understoodt-hat two or more filaments willbe provided-dep'ending uponthe thickness of the film to be-deposited. It-is to be understood further that then-laments may' be of any'forinsuchas a' straight-w'ire, several twisted wires, a basket, etc. The metal to he evaporated carried by the filament 6, an'd the point from which greatest radiation-takes place willhe' at the centerof-the filament. I p

e The rotary head for-supporting the "carriers to be coated is eonstrueted as a unitarystrueture are is mounted onthef-upper-ends of supporting rods, '2 a, 2 b, and and involves" supporting frame including r0 x1; nsiOnsZ'aQZbf, 'ZcQf'Zd; thelower ends of w hare provided ithsockets for receiving theireaueed---extensiohs on he upper ends of'rdsZm-flb, 22c ahdfld. A pafirof horizontal cross-bars l andj B is'secu-red to-the upper en'dsof rod extensions 2a -'2d and"-2b'-2c",-re'- spectively, "see Figure-1 and a third'crOSs-barQ is seeuredftdb'ars i arrd' a, at the-oenters thereof,

Supported from crossbars l and 8 by means of short spacers la, 1b, 8a. and 8b is an inverted annular pan or casing Ill formed of metal, such as copper or brass. Casing supports within the annular space thereof a heater wire l l which extends around the annular part of the casin iii in zigzag fashion and is connected to suitable insulated terminals Ila and ill). Heater wire I I is for the purpose of maintaining the carriers at a proper temperature during the evaporation process. A vertical rod i2 is'rigidly supported in a block 9a carried by crossbar 9 and extends downwardly into the central opening in. the annular casing It. The lower end of rod 82 is provided with a fixed sleeve l2a to which is attached a, circular plate It having gear teeth 53a formed in the edge of a conical flange at the periphery thereof. Gear i3 is held rigid and stationary by the vertical shaft l2.

. The main rotary ,elementof the movable car riage for supportingthe carriers to be coated comprises a circular disk M journaled upon the shaft i2 and resting upon the sleeve 2a. This disk is provided with a downwardly extending conical-flange Ma formed at its periphery and a second conical flange Mb of smaller diameter extends downwardly from the lower face of disk M. This disk is driven by means of a sprocket l5 journaled on the shaft 12 below the crossbar 9. The sprocket I5 is secured to the disk It by means of a number of vertical spacers Ida. A smaller sprocket I6 is journaled in a bearing supported by the left end of crossbar 9 and drives the larger sprocket by a chain belt ltd. The lower end of the shaft of sprocket it carries a slotted sleeve lEb which fits over the upper end of a driving shaft ll having a transverse pin l'la extending into the slot of the sleeve liib. The driving shaft ll extends downwardly through an aperture in base plate 2 and through a vacuum-tight packing I8 mounted on the plate 2 and is driven from any suitable source of power.

A plurality of spindles [9 are journaled in holes formed near the lower edges of conical flanges Ma and Mb of rotary plate M as shown in Figure 3. Each spindle passes through a sleeve 2!] pcsitioned between the flanges [4a. and Nb, and the sleeve is secured to the spindle by any suitable means such as the screw shown in Figure 3.

The outer endof sleeve .20 carries a smallspurgear 2| which meshes with the teeth I30. on the stationary gear I3. The spindles l9 extend radially beyond the edge of disk M and rotate below the annular heater casing in supporting the heater wire ll. Any suitable number of spindles may be provided, but in the arrangement illustrated in Figure 4 of the drawing twenty spindles are mounted on the rotary head. Rotation of the disk l4 about the shaft l2 causes the spindles I9 to rotate with the disk l4, andat the same time, engagement of the gears 2! with the gear l3 causes the spindles to rotate about their own axes. Only one spindle H has been shown in Figure 3 for the purpose of avoidin confusion in the drawing.

Each spindle is provided with a pair of removable chuck pieces lea having oppositely facing conical ends between which the tubular carrier 22 is mounted. Only one carrier has been illustrated in Figures 3 and i, but it will be understood that a carrier is mounted on each spindle.

In the formation of certain types of resistor elements for use as attenuators, it is desirable to produce a metallic film on the carrier in which spindles. 19, as shown in Figure 3.

the thickness of the film in different linear sec tions is not the same. For example, in producing an attenuator for a coaxial cable, the film deposited on the tubular carrier would have a central section of a certain thickness of film, and two matching sections of a greater thickness of film. For the purpose of producing metallic films of this type, the present invention involves a shield arrangement for shielding the central portion of'the tubular carrier over a portion of the circular path through which the carriers travel. This shielding arrangement involves a bar 23 secured to the lower face of stationary gear 13 and having the ends thereof bent downwardly substantially parallel to the direction of Bar 23 supports an annular shield 24 which is positioned to shield the central portion of the tubular carriers 22 when the carriers :pass behind the shield. As will be seen from Figure 4, theshield 24* does not extend entirely around the closed path through which the spindles move, and the cen-- tral portion of the carriers are exposed to the radiation only during the time that the carriers are passing over the gap in the shield. By adjusting the extent of the gap in the shield, different thicknesses of the film may be obtained on the central portion of the carrier. It is obvious, of course, that the end sections of the tubular carriers, which are not shielded by the shield 24,

are exposed at all times to the radiation and the films deposited on these sections will be thicker than the film deposited on the central section. By tapering the width of the shield,

the thickness of the film deposited over the shielded portion of the carrier will vary in thick ness along its length.

As shown in Figure 3, the spindles l9 are arranged at an angle to the horizontal so that the spindles are normally directed at right angles to the direction of the source of radiation. This angular positioning of the carriers is not' essential, although it is desirable for obtaining the same thickness of coating at the two ends of the carrier.

In operation of the apparatus, it is desirable for best results that the rotary head should be rotated through one or more complete revolutions during the evaporation process. Very good results have been obtained in a machine where the head rotates about ten revolutions per minute and the spindles rotate on their axes at a speed of about revolutions per minute. Depending upon the thickness of the film desired and the kind of material being evaporated, theentire process will take from 2 minutes to 2 hours or more. The distance of the spindles l9 from the source of radiation is not critical, and a compromise must be made between the degree of uniformity and the thickness of the -film deposited in a given time. In the machine referred to above, the spindles were located about '15 inches above the vaporizing filament.

In using the apparatus, the procedure followedis substantially the same as that described in the copending application referred to above.

It is not essential that the spindles I!) be arranged radially of the rotary head, but these spindles could be arranged vertically in parallel relation, and revolving around the source of radiation.' Also, while the'rotary head is especiallyv designed for use with tubular carriers,'it is obvious that the head may 'be-used as a'rotating' frame for supporting fiat plates which would be mounted on the frame and would not rotate about individual axes.

As shown in Figure 2, an inverted cylindrical cup-shaped heat shield 25 may be arranged to cover the rotary head and to shield the bell-jar from stray radiation. The shield may be formed of sheet copper or other good shielding material.

It is also obvious that the construction of the rotary head may be reversed from that shown in the drawing, that is, disk l4 may be held stationary and provided with a circular arrangement of gear teeth, while the spindles 19 would be journaled on the disk I3, and this disk would be made rotatable by arranging shaft 12 to turn in its support. In this case, the shield supporting bar 23 would be supported independently of the shaft 12.

We claim:

1. Film forming apparatus comprising a mov-- ably mounted carriage having means thereon for supporting in a closed path a plurality of car--v riers to be coated, a vacuum chamber enclosing said carriage, a source of molecular radiation arranged within said chamber to simultaneously irradiate said carriers, said radiation having different intensities at different points around said path, and means for moving said carriage to cause each of said carriers to move completely around said closed path while being exposed to said radiation.

2. Apparatus according to claim 1 and including a shield mounted within said chamber, between the path of said carriers and the source of radiation, and arranged to shield selected portions of said carriers as they move around said closed path.

3. Apparatus according to claim 1 wherein said carrier supporting means extend across said path transversely of the direction of movement around said path, and including a shield mounted within said chamber between the path of said carriers and said source, and arranged to shield selected linear portions of said carriers, said shield being arranged along said closed path but having a ap therein to permit a limited coating of said shielded portions.

4. Apparatus according to claim 1 and including means embodied in said movable carriage for rotating each carrier supporting means about an individual axis simultaneously with movement thereof around said closed path.

5. In apparatus for depositing films upon carriers in which the carriers to be coated are enclosed Within a bell jar having a base upon which is supported a vaporizing filament and four vertical standards surrounding the filament, the combination of a unitary carrier-supporting head removably supported on said standards comprising an annular heater casing having anopen face directed downwardly, an annular heater filament supported in said casing, and a rotary carriage having its axis arranged coaxially with said heater casing and having means thereon for supporting said carriers for movement in a circular path below said annular heater casing.

6. Apparatus according to claim 5 wherein said rotary carriage comprises a rotary disk having a plurality of spindles journaled thereon and extending radially therefrom, each of said spindles being adapted to support a carrier in the form of a tubular element surrounding the spindle, and

including means for rotating each spindle about its axis simultaneously with the rotation of said disk.

7. Coating apparatus according to claim 5 and including an annular shield supported below said carriage and arranged to shield selected portions of said carriers.

8. Apparatus for depositing films upon tubular carriers comprising, in combination, a base member, a vaporizing filament supported on said base member, a number of vertical standards supported on said base member surrounding said filament, a head structure mounted across the upper ends of said standards, a vertical shaft rigidly secured to said head structure and extending downwardly therefrom above said filament, a circular carriage journaled on said shaft, a plurality of spindles journaled on said carriage and extending radially therefrom, each of said spindles being provided with means for supporting a tubular carrier surrounding the spindle, and means for rotating said carrier and for simultaneously rotating said spindles about their individual axes.

9. Apparatus according to claim 8 and including an annular heater supported by said head structure and positioned above the path of travel of said spindles for heating said carriers.

10. Apparatus according to claim 8 and including an annular shield member supported from the lower end of said vertical shaft and positioned to shield selected portions of the carriers mounted on said spindles.

11. Apparatus for depositing films upon tubular carriers comprising, in combination, a base member, a vaporizing filament supported on said base member, a number of vertical standards supported on said base member surrounding said filament, a head structure mounted across the upper ends of said standards, a vertical shaft rigidly secured to said head structure and extending downwardly therefrom above said filament, a circular carriage journaled on said shaft, a plurality of spindles journaled on said carrriage and extending radially therefrom, each of said spindles being provided with means for supporting a tubular carrier surrounding the spindle, means for rotating said carrier and for simultaneously rotating said spindles about their individual axes, an annular heater supported by said head structure and positioned above the path of travel of said spindles for heating said carriers, and an annular shield member supported from the lower end of said vertical shaft and positioned to shield selected portions of the carriers mounted on said spindles.

STANLEY ADAMS JOHNSON.

HUBERT W. SCHLEUNING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 331,757 Baldwin Dec. 8, 1885 990,645 Engleman Apr. 25, 1911 2,260,471 McLeod Oct. 28, 1941 2,369,764 Ullrich Feb. 20, 1945 2,380,509 Emerson July 31, 1945 2,398,382 Lyon Apr. 16, 1946 2,432,950 Turner et al. Dec. 16, 1947 Certificate of Correction Patent No. 2,522,272

A September 12, 1950 STANLEY ADAMS JOHNSON ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 17, after the word arrangement insert for driving the movable carriage, a shieldjor shielding;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1950.

[sun] THOMAS F. MURPHY,

' Assistant Commissioner of Patents. 

